Conjure a mental image of an ancient empire and you’re probably picturing an iconic site like the Acropolis in Athens or Rome's famous forum. Yet many seemingly unremarkable modern towns were once imperial strongholds too. Some were short-lived capitals of famous empires, while others were the long-lasting first cities of nations now lost to the mists of time. These are the most surprising modern settlements that were once renowned centres of power.

In AD 408, the emperor Honorius made a startling declaration: Rome was old news, and the capital of the declining Roman Empire was now the northern city of Ravenna. The new capital was surrounded by marshland and easier to defend against barbarian tribes, but Honorius’s cunning plan to save the empire didn’t succeed, as Rome’s enemies simply bypassed Ravenna and took Rome anyway. As a result, the empire fell apart in less than 70 years, leaving Ravenna the capital of a new barbarian-controlled kingdom.

The town that ruled over the collapse of the Roman Empire is now home to just over 150,000 people, and its late-Roman past is most evident in two ancient monuments. The octagonal Baptistery of Neon is Ravenna’s oldest surviving structure, and contains stunning ceiling mosaics. The Mausoleum of Galla Placidia (pictured) was named for Emperor Honorius’s wife, and, although she was never actually buried there, it does contain another stunning collection of mosaics.

The east-central city of Kaifeng is comparatively small by Chinese standards, with 1.7 million people living within its limits. But the city was once one of China's so-called 'seven ancient capitals', specifically during the 11th century when it was the capital of the Northern Song dynasty. Perhaps the largest city in the world during its imperial heyday – though it was barely a third of its current size – Kaifeng was a thriving metropolis conveniently situated at the centre of China’s burgeoning canal network.

Kaifeng technically served as imperial capital on eight separate occasions. Experience the full span of the city’s past by seeing the mid-6th century Daxiangguo Temple and the 17th-century walls which surround the old town. Perhaps the city's most remarkable building of all is the 13-storey Iron Pagoda, the first iron tower in the world, which was built during Kaifeng’s zenith in 1049. The reconstructed government offices of the Song period are used for colourful recreations of imperial life by costumed actors.

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Wetzlar spent centuries as an important part of the Holy Roman Empire (one of Europe's most powerful monarchies for more than 800 years), and was given the right to rule itself with a degree of autonomy as early as AD 1200. But in 1689 Leopold I selected Wetzlar as the new home of the Imperial Chamber Court. For the next 117 years Wetzlar's judges settled disputes from across central Europe, and the city enjoyed enhanced status as one of the empire’s honorific capitals.

Today, Wetzlar is a small town of 55,000 people, and is dotted with historic buildings. It’s difficult to miss the cathedral, which dominates the skyline, and a few winding streets away you'll find the former town hall which was commandeered by the Imperial Chamber Court. The best way to experience Wetzlar is simply to wander the picturesque old town taking in what was once the Holy Roman Empire’s final bastion of justice.

For more than 300 years the rulers of the Ethiopian Empire roved around their realm, never staying in one place for long. That all changed in 1635, when Emperor Fasilides became fed up the nomadic lifestyle and yearned for a place to call home. He founded a city that served as capital for the next two centuries and gave its name to the Gondarine period – a golden age in Ethiopian history. Gondar expanded as each new ruler sought to leave his mark with a new palace, church or other grand building project.

Gondar is now a buzzing city with a population of around 400,000 – not small but not a patch on the several million that call modern-day capital Addis Ababa home. Its royal roots are protected behind the high walls of the Fasil Ghebbi – literally 'Fasil's enclosure'. This vast World Heritage Site contains six castles, three churches, a library, a bathhouse and cages that once held the lions of the royal menagerie. Be sure to take a guided tour to bring the machinations and intrigue of court to life.

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The 57-year-long Nicene Empire may appear short-lived at first glance, but it was part of a much longer-lasting realm. The Byzantine Empire was almost a thousand years old when European crusaders sacked and captured its capital Constantinople in 1204. The Byzantine aristocracy fled south and established a new court at Nicaea until they recaptured Constantinople in 1261. But the old order didn’t hang onto the Turkish city and one-time capital for long – Nicaea was captured by the Ottomans in 1331, and renamed Iznik.

Eight hundred years on from its moment in the sun, Iznik is now home to fewer than 25,000 people. Many of its historic sites date to the Ottoman period, but relics of the Byzantine era remain too. City walls still ring the town, while the Hagia Sophia church was converted to a mosque but retains its Byzantine structure. Another Byzantine-era church was recently discovered submerged in Iznik Lake, and plans are now afoot to convert it into an underwater museum.

For much of its early history the mighty Mughal Empire was based in the city of Agra, known today for the world-admired Taj Mahal, but not for a 14-year stretch starting in 1571. In a gesture of thanks to Sufi saint Shaikh Salim Chishti, who correctly predicted the successful birth of an heir to the Mughal throne, Emperor Akbar moved his entire capital 22 miles (35km) west to the holy man’s home in Sikri. Akbar soon transformed the tiny village into Fatehpur Sikri – 'the city of victory'.

These days, Fatehpur Sikri is once again a town of a few thousand inhabitants who mostly service the tourist trade. Visitors come from afar to see the stunning Jama Masjid mosque with its colossal Buland Darwaza gateway, and the short-lived capital’s three palaces. Legend holds that the trio of residences were built for Akbar’s three wives – one Christian, one Hindu and one Muslim. The scale of building in the largely abandoned city still amazes, especially since the capital barely made it into its teenage years.

The Vikings weren’t a unified people, and Scandinavia was peppered with small, warring states ruled by kings, jarls and chiefs. But one place with a credible claim to be the heart of the late Viking realm was Roskilde, a settlement on the island of Zealand. Founded around 980 by Harald Bluetooth, King of Denmark and later of Norway, Roskilde coalesced around Bluetooth’s palace and a church that became the traditional burial place of Danish kings.

The 50,000 Danes living in present-day Roskilde make a good living off the backs of their Viking forebears. Visitors making the short journey from Copenhagen can board a longship at the Viking Ship Museum and view Bluetooth's tomb (pictured) in Roskilde Cathedral (though there is now some doubt over whether he was actually buried there). The town has a foot in the 21st century too through the Ragnarock Museum for Pop, Rock and Youth Culture, and the largest annual music festival in northern Europe.

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Imperial rulers beware if Harran becomes your capital. This town served as capital for three different empires – the Neo-Assyrian (612-609 BC), the Umayyad Caliphate (AD 744-750) and the Numayrid Emirate (AD 990-1081) – but each time, the empire it ruled was in its death throes. The Mongols didn’t make the same mistake – when they captured Harran in 1260, they ravaged the historic town and left it largely abandoned. Only in the 1840s did Harran regain a permanent resident population.

Now, around 10,000 Turks live in Harran and help to look after the village’s ancient remains: the ruined citadel Harran Kalesi and the collapsed  Ulu Cami mosque (pictured) dating from the Umayyad period. Harran’s distinctive beehive houses are largely 20th-century constructions – mud and camel dung walls don’t stand forever – but the modern homes are built in the same style as those from the Assyrian era, and they are surprisingly cool inside.

When the legions of Roman emperor Claudius crossed the sea to England in AD 43, London was little more than a swampy village on the banks of the Thames. For the Romans the big prize was Colchester, the capital of the powerful Catuvellauni tribe who bitterly resisted the invasion. After their victory, the Romans made Colchester their imperial capital, which it would remain for 17 years. It lost its status to fast-growing London thanks to Boudica, Queen of the Iceni, whose rebellion against Rome in AD 61 burned most of Colchester to the ground.

The ashes of Britannia’s first capital can be found underneath Colchester Castle. Although the present fort is of 11th-century Norman origin, it was built on the burned-out foundations of the vast Temple of Claudius. Boudica may have caused Colchester’s downfall, but it was recently granted city status by a different queen – Elizabeth II issued the letters patent in one of her last royal acts before her death.

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Japan had been ruled by 42 emperors and empresses prior to the accession of Empress Genmei in AD 707, but she quickly broke from the norm by settling in a permanent capital for the first time. The place she chose was Heijo – known today as Nara – and the town was quickly laid out in a grid pattern, ready for the empress’s arrival in 710.

Nara only served as capital for 74 years, until Emperor Kammu moved his court to Heian-Kyo (now Kyoto). Kammu wanted to distance himself from Nara’s powerful Buddhist establishment, and the imperial household and national religion still leave their mark on the town of 360,000 inhabitants today. Don’t miss Todaiji Temple (pictured) and Heijo Palace – both built during the era that emperors called Nara home. Horyuji Temple is even older and claims to be the world’s oldest wooden building.

Valladolid’s time in the Spanish spotlight was brief. King Philip III moved from Madrid to Valladolid in 1601 on the advice of the Duke of Lerma, seemingly so the duke could buy land around the old capital for a reduced price. After only five years, an outbreak of plague sent the court scurrying back to Madrid – and the Duke of Lerma made a fortune by selling his new landholdings back to the crown. Today it barely scrapes into the top 20 largest cities in Spain.

Valladolid’s old town boasts some of Spain’s finest Renaissance architecture. The cathedral was intended to be the largest in all Europe, befitting the city’s status as the Spanish capital. When the king returned to Madrid, the architect’s plans were downsized – but the ensuing building is still awe-inspiring. Plaza Mayor became the model for Madrid’s similarly named central square, and the grand Colegio de San Gregorio now houses the National Museum of Sculpture. Pictured here is San Pablo Church.

It’s difficult to imagine that the modern Ethiopian town of Axum was once the capital of an empire that rivalled Rome and Persia. Nowadays, fewer than 100,00 people live among its ancient ruins – the most striking of which are enormous obelisks named stelae. The 160-tonne Obelisk of Axum was recently returned from Italy after being seized in the 1930s, while the Great Stele never lived up to its name – it probably collapsed and broke during construction.

During the 5th and 6th centuries the Christian Kingdom of Axum was a global power – or as close as you could get to being a global power in the 5th and 6th centuries – ruling a vast swathe of East Africa as well as a strip of the Arabian Peninsula. The kingdom interacted regularly with the Greco-Roman world, controlling trade between Rome and India and adopting Greek as an administrative language. A series of wars with Persia stripped Axum of its Arabian territories in the late 6th century, and in the 7th century the kingdom entered irreversible decline.

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In the dying days of the 17th century, British colonists living in the New World decided to relocate the capital of the Virginia Colony from accident-prone Jamestown – whose statehouse had burned down twice – to a tiny, inland village known only as Middle Plantation. From these humble beginnings, the town of Williamsburg grew. It served as Virginia’s capital until the American Revolutionary War, when governor Thomas Jefferson feared it was too vulnerable to loyalist attacks.

After American independence, Williamsburg quickly slid into decline. It was rescued by tourism in the early 20th century, when hordes of Americans began to descend on the town in search of their nation’s origins. Now, around 15,000 Virginians live in the shadow of the town’s busiest attraction – a living history museum of restored and replica colonial-era buildings peopled by costumed actors. It offers everyday Americans a chance to walk in the footsteps of the founding fathers.

The Ottoman Empire was on the rise when Sultan Murad I invaded Bulgarian-controlled territory and captured the former Roman city of Adrianople in the 1360s. He soon renamed his new possession Edirne and made it the Ottoman capital, signalling that the Muslim empire intended to keep hold of its Balkan lands for the long term. Edirne remained the seat of the sultans for nearly a century, until the Ottomans captured an even more prestigious city from the Christians: Constantinople, now known as Istanbul.

Nowadays, Edirne marks the northwest frontier of Turkey and 180,000 people call it home. Many of its early Ottoman monuments and buildings are still in good condition, including three 15th-century mosques and the imperial palace commissioned by Sultan Murad II. The main sites are all within walking distance of each other in the pleasant riverside city, and, as Turkey’s gateway to Europe, it’s a melting pot of European and Anatolian food and culture.

The Romans enjoyed the spa waters of Aachen’s natural springs, but the town became more important after the legionaries left when the Frankish kings built a castle there. A few decades later, King Charlemagne made the town his capital thanks to its strategic location within his lands. He subsequently extended his holdings so much that Pope Leo III named him the new Emperor of Rome on Christmas Day, AD 800 – a move that gave birth to the long-lived Holy Roman Empire.

In the present day, the meandering borders of the Low Countries mean that Aachen is a German town that sits right next to both Belgium and the Netherlands. Its 250,000 residents also live in the shadow of Aachen Cathedral (pictured), built on Charlemagne’s orders and still the last resting place of his body. Numerous artefacts from the early Holy Roman Empire can be found in the Cathedral Treasury and many medieval buildings stand near the cathedral's precincts, having survived the horrors of 20th-century war.

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